Typical low cost solid state force sensors mount a sensing element in an external package. The sensing element is attached to an actuator that extends outside of the housing and that communicates an external force to the sensing element within the housing.
The actuator in this type of construction can negatively affect the performance and accuracy of the sensor. For example, the construction tolerances of the sensor, of the sensor mounting system, and of the actuator can result in the actuator having an improper position with respect to the sensing element. Improper positioning of the actuator can in turn lead to sensing errors.
The present invention eliminates the need for an actuator by providing a sensor package that mounts the sensing element in a planar orientation so that the sensing element can interact directly with the force that it is intended to sense. This mounting arrangement, therefore, eliminates the performance errors and sensitivity loss associated with the sensors that use some form of actuator interface between the sensing element and the force that is sensed.
Also, the sensing element of the present invention may have a flat, planar surface so that it can better interface with certain compliant materials such as human skin. Conventional force sensors typically cannot maintain a flat surface across the surface of a force sensor package. Moreover, the sensor package of the present invention has a simple construction and has few components resulting in a relatively low manufacturing cost, it is relatively simple to automate, and it can be made relatively thin for greater accuracy.